SANITY AT LAST

Whatever The Dangers Of Cannabis, Draconian Laws Make No Sense

IS CANNABIS more - or less - harmful than its legalised cousins
alcohol and nicotine? Last week, bang on cue, this hoary old question
surfaced yet again as the British government signalled its intent to
relax the laws on cannabis possession, and join what is becoming an
almost global trend.

Other countries have already taken steps towards decriminalising
possession, but nobody expected the same from Britain (see p 12). The
admission that cannabis is not as harmful as heroin and cocaine goes
against everything it's been saying for years. It also leaves the US,
which is sticking to this hardline position, increasingly isolated.

But not quite alone. One of the strongest attacks on Britain's U-turn
came from the nation's bestknown neuroscientist, Susan
Greenfield-Oxford pharmacologist, TV presenter and now a member of
the House of Lords. In a thundering broadside in a daily paper,
Greenfield blasted liberal campaigners who seek to play down the
evidence that cannabis permanently damages the brain. It's good to
see scientists of Greenfield's standing voicing strong opinions on
public issues. However, having reported on the science of cannabis
for many years, we have to disagree with her conclusions.

To take just one example, she points out that some 7000 milligrams of
alcohol are needed to achieve intoxication, whereas for cannabis the
figure is just 0.3 milligrams: cannabis is far more potent and hence
far more dangerous, she reasons. But what this really means is that
you have to have 20,000 times as much alcohol coursing through your
veins before you feel the effects. By then your liver is having to
work overtime. Alcohol certainly lacks cannabis's ability to act on
brain receptors in a potent and specific manner: that is one reason
why booze can be so deadly.

A number of cannabis users do develop a serious dependency problem.
And in excess the drug can lead to poor concentration, even bouts of
paranoia. But permanent brain damage? A few lab studies have, it's
true, reported that cannabis-like substances can harm nerve cells
cultured in the test tube. But such cultures are notoriously fragile,
and other studies have found no signs of brain damage in animals
given doses far higher than those needed to produce intoxication in
humans.

And even if they hadn't, it wouldn't matter - at least not as far as
changing the laws on cannabis go. The evidence from other countries
is that more relaxed laws do not lead to more youngsters using the
drug. Wherever cannabis lies in the league table of harmful
substances, there seems little point in imprisoning people for
possessing small amounts unless this is likely to make the drug less
popular. And all the signs are that it doesn't.